Bellows adapted to serve as transitions or flexible passages between articulating vehicle segments (such as rail-borne or road vehicles) are generally made of a polymer which is reinforced by inlaid webs of fabric. This material may also be spoken of as a structure consisting of a fabric web coated on both sides with a natural or more especially synthetic rubber or polymer. Such a web of material formed as a bellows is inherently soft or deformable but is not elastically deformable; the relative deformability of the bellows required owing to the motion of the vehicle only results from the deformation of the web of material into a bellows. Generally, it is not only a single material web which is formed into a bellows and it is more usual for a number of strips of such material webs to be connected together along their longitudinal edges so as to form a concertina-like bellows. The connection is for instance by sewing or bonding and/or by encircling clamped-on sections.
Generally bellows have the same outer profile in the circumferential direction and apart from the corners have generally the same depth of fold, although the requirements as regards softness or the ability to yield are quite different. In fact, the side walls of the bellows should be so stiff in the vertical direction that the bellows keeps its height while the ceiling of the bellows and the floor, if any, are to be able to relatively soft in the horizontal planes in order not to overly impede the necessary relative lateral shift of vehicle segments.
In order to at least partly take this circumstance at least partly into account there has already been proposal to have a triple or multiple folding of the bellows in the transitions between lateral bellows walls and the ceiling of the bellows so that each fold is again folded into itself, because without such a measure the transitional arches would cause the bellows to be particularly stiffened in the transverse direction. This feature is however relatively expensive to implement and its accordingly seldom to be found and there are no other measures designed to allow for the different requirements in different parts of the bellows which have been put into practice because of the complexity and expense involved.
On the other hand it has recently become possible to influence the softness of a web of material of polymer compounds by causing energy to act on the web, more particularly by irradiating it with electron or x-ray beams (see the German unexamined specification 3,629,701). By having a suitable intensity of radiation it is possible for a relatively hard polymer to be softened while with another intensity a relatively soft polymer may be rendered harder by increasing or decreasing the number of inter-molecular bonds.